first of all, Thank you Jeesh for this wonderful thread.
You still need to start somewhere, you still need homegrown coaches at least as a backup. You can't always afford overpriced overseas coaches, it is unrealistic. Homegrown coaches can be a huge asset to the development of the Cricket culture, They have an upper hand at talent scouting, lol exactly the ideas Jeesh mentioned in his first paragraph as I typed this without reading it.
However as Observer and Ian Pont pointed out, we should not be overly reliant on them to the extent that we are lacking in Quality. Nevertheless, Homegrown coaches are a must, absolute must at least at the domestic scenes. Remember, it was Khaled Mahmud Sujon who coached and Advised Ziaur Rahman to open the batting and he found some success and found a spot at our T20 Squad. He still has a lot of work to do, but so far Ziaur Rahman has shown little success(considering where he came from and the amount of batting coaching he received it is not that all bad) I too dream of the day a local Coach like Aminul Islam Bulbul will take up the coaching job...communication, honesty, commitment problems should be resolved in an ideal world.
We need a combination of Foreign and Domestic coaches who can groom exciting talents into world class players. Quality coaching is key, coaching all the technical aspects of the game in addition to coaching in such a manner where the coach is able to clearly communicate with the players under him to such an extent that the player can feel confident and assert his dominance on the cricket field with ease based on the learned techniques.